Democratic state Sen. Katherine Clark raised $261,000 in her first quarter as a candidate for the 5th District, according to an email she planned to send supporters Thursday.

Clark is part of an evolving field ready to run for the heavily Democratic 5th District if its current occupant, Democratic Rep. Edward J. Markey, wins the upcoming special election for Senate.

Public polls show Markey leads his Democratic and Republican opponents in the race to succeed now-Secretary of State John Kerry in the Senate. Rep. Stephen F. Lynch is also running for the Democratic nomination.

Former U.S. Attorney Michael Sullivan is the front-runner for the GOP nomination. State Rep. Dan Winslow and Gabriel Gomez, a private equity investor and former Navy SEAL, are also running for the Republican nod.

The special primary for the Senate seat is April 30, and the general election is June 25.